1. Field of the Invention
The present invention relates to an optical scanning system which is used for a writing optical system such as a laser printer, a laser facsimile, a digital copying machine, etc. and is used for an optical scanning system of a measuring apparatus such as a laser face flaw detector or the like. More particularly, the present invention relates to an optical scanning system using an f.theta. mirror.
2. Description of the Related Art
Conventionally, an optical scanning system has been known in which a light beam emitted from a light source such as a laser light source is deflected at an equal angular velocity by a deflector, and the deflected light beam is focused on a scanned face as a light spot through an f.theta. lens or the like so as to carry out an optical writing and an optical scanning. This optical scanning system has been used for a writing optical system such as a laser printer, a laser facsimile, a digital copying machine, etc. and for a measuring apparatus such as a laser face flaw detector or the like.
In such an optical scanning system, for the purpose of making a device compact, reducing the number of components, developing an assembling accuracy, improving an optical performance, and so forth, there has been proposed an optical scanning system characterized in that a base supporting a light source portion, a base supporting a bearing of a deflector and a base supporting an image forming lens of the optical scanning system are unitedly molded (Japanese Utility Model Publication No. 63-4172).
In the optical scanning system disclosed in the above-mentioned Publication, the base supporting the light source portion, the base supporting the bearing of the deflector and the base supporting the image forming lens are unitedly molded. That is to say, the optical scanning system disclosed in the Publication includes "a supporting portion", and the light source portion, the bearing portion, and the image forming portion are fixed onto "the supporting portion" as separate components from an optical housing (an optical box) of the optical scanning system.
Especially, an f.theta. lens is used for the image forming portion in the embodiment of the Publication. In this case, the f.theta. lens is made of a transparent material, and it is not considered that the f.theta. lens is unitedly molded with the optical housing. In contrast, it is possible to consider that the optical housing including the f.theta. lens is unitedly molded by using the transparent material. However, this case necessitates the drawing of a mold in a direction vertical to a surface of the f.theta. lens (an optical axis of the lens), and it is therefore practically difficult to mold the f.theta. lens unitedly with the housing.